Antibodies that neutralize most salvecoviruses, including SARS-CoV-2 mutants

As of April 21, 2022, coronavirus 2 (SARS-CoV-2), a severe acute respiratory syndrome that causes coronavirus disease 2019 (COVID-19), has infected more than 507 million people worldwide. , More than 6.21 million people have died. Several SARS-CoV-2 mutants have emerged, become more contagious, and have the ability to evade the immune system.The threat of continued zoonotic spillover events hinders the development of widespread and effective interventions coronavirus There is a possibility of a pandemic.

study: The antibody class with the common CDRH3 motif widely neutralizes salvecovirus. Image Credit: picmedical / Shutterstock.com

Background

Several isolated anti-SARS-CoV-2 monoclonal antibodies (mAbs) are associated with SARS-CoV-2 and other salvecoviruses that are subgenres containing both SARS-CoV and SARS-CoV-2. On the other hand, it has been reported to have neutralizing activity. Such broadly neutralizing mAbs are useful not only for current pandemics, but also for the treatment of future zoonotic diseases caused by the salvecovirus.

Therefore, it is important to identify the various specificities of these antibodies to determine the best anti-pandemic agent. In addition, identifying commonalities and defects between mAbs will help in the development of pan-salvecovirus vaccines.

New research published in Scientific translation medicine Three mAbs that broadly neutralize salvecovirus were isolated and virological and structural studies of these mAbs were performed. Here, the researchers also performed a comprehensive comparative analysis of these mAbs with the other nine mAbs previously reported to have broader activity.

About research

In the current study, serum samples were collected from convalescent COVID-19 patients and identified mAbs with broad neutralizing activity. Patient 10 was reported to be symptomatic in March 2020 and blood was drawn in April 2020.

Patient 11 was reported to be symptomatic in November 2020 and was vaccinated twice with the mRNA-1273 vaccine in January and February 2021. Blood was drawn from patient 11 one week after the second vaccination.

Subsequently, SARS-CoV-2 spike (S) trimmer and receptor binding domain (RBD) proteins were expressed and purified. B.1.351 S Trimmer-specific memory B cell selection is performed using peripheral blood mononuclear cells (PMBC) collected from patients 10, patient 11, and healthy donors, followed by single cell B cells. The receptor sequence has been determined. S antibody transcripts were identified using analytical protocols, followed by antibody transcript annotations, and antibody expression and purification.

The neutralizing activity of the antibody is different for the SARS-CoV-2 omicron mutant (BA.1). (A) Mutations in Omicron variant BA.1 (B.1.1.529.1) have been shown in the complete SARS-CoV-2S trimmer. The SARS-CoV-2S protein structure was downloaded from PDB7KRR. The red circle represents the S1 / S2 cut site. SD1, subdomain 1; SD2, subdomain 2. (B) A neutralization curve for selected mAbs for VSV pseudotypes containing D614G (WT) and B.1.1.529.1S proteins is shown. A 50% horizontal dotted line indicates an IC50 value. (C) The neutralization titers (IC50) of selected mAbs for VSV pseudotypes containing D614G (WT) and B.1.1.529.1 S proteins are summarized. The data is shown as the mean ± SD of the three technical replicas.

The antibody binding test was accomplished by enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR) analysis. Competition and epitope mapping of the angiotensin converting enzyme 2 (ACE2) receptor was performed by ELISA.

S protein constructs were then prepared for cell surface expression and pseudovirus production. Binding of cell surface S proteins was performed by flow cytometry.

Production of recombinant vesicular stomatitis virus (rVSV) pseudovirus Glycoprotein A pseudovirus neutralization assay was performed after replacement with SARS-CoV S protein, S protein from SARS-CoV-2 or one of its variants, or other salvecovirus S protein.

Real virus was propagated and titrated, followed by neutralization with purified monoclonal antibody. The protein was purified for cryo-electron microscopy (cryo-EM) and crystallography, followed by cryogenic EM grid preparation, data collection, and analysis.

We also performed footprint analysis combining RBD and antibody Fab models, followed by crystallization and data processing of RBD and Fab complexes of various monoclonal antibodies.

With array storage Phylogenetic analysis Made against salvecovirus. Epitope and paratope analysis was performed on antibodies 10-40. Finally, mouse models infected with SARS-CoV and SARS-CoV-2 were pretreated with 10-40 to determine their role in infection protection.

Investigation result

Of the total 58 mAbs isolated and characterized, three (10-40, 10-28, and 11-11) bound to the SARS-CoV-2 S protein and SARS- of variants D614G and B.1.351. .. CoVS protein. These three mAbs were found to recognize epitopes within the RBD and inhibit the binding of S proteins to the human ACE2 receptor.

Nine RBD-specific antibodies reported to be effective against salvecovirus include DH1047, S2X259, REGN10985, ADG-2, 2-36, COVA1-16, CR3022, S2H97, and S309. I was there. In addition, 10-40, 10-28, and 11-11 utilize the GHV4-39 * 01, IGHV3-30 * 18, and IGHV4-31 * 03 heavy chain V (variable) genes and GLV6-57 * 01. I found out. IGKV1-39 * 01, and IGLV1-40 * 01 light chain genes.

With the exception of CR3022, all mAbs were able to neutralize all strains of SARS-CoV-2, with ADG-2 being the most potent. For SARS-CoV, DG-2, 10-40, S2X259, and DH104 showed neutralizing activity. However, only 10-40 and DH1047 were able to recognize 10 non-SARS-CoV-2 salvecoviruses, and none were aware of the Middle East Respiratory Syndrome virus (MERS).

In addition, 10-40, 10-28, and S2H97 bind to all RBDs of the six salvecoviruses except the SARS-CoV-2 and SARS-CoV substrains. Only 10-40 and S2H97 were able to neutralize the currently predominant circulating SARS-CoV-2 omicron mutants.

Three antibodies were reported to recognize areas inside RBD that were hidden in RBD down confirmation. To this end, 10-40 has been reported to bind to highly conserved epitopes that allow binding to all salvecoviruses.

In addition, 10-40 could be bound via its CDRH3 and CDRL2 regions, as well as additional hydrogen bonds and salt bridges. In addition, the “YYDRSGY” motif from IGHD3-22 was identified at 10-40 along with other broadly neutralizing mAbs that may bind to specific epitopes of salvecovirus. Prevention of weight loss and decreased viral titers were reported in mice pretreated at 10-40.

Conclusion

Current studies have identified 10-40 as a potential anti-pandemic agent because it was effective against most salvecoviruses.This mAb was also shown In vivo A protective effect that suggests that it can be performed for human use. Further research is needed to develop a pan-salvecovirus vaccine that can provide protection against future pandemics.

Limitations

Antibodies to all salvecoviruses have not been tested in the current study. In addition, it was not possible to carry out neutralization studies of all salvecoviruses. An additional limitation was that current studies could not verify whether the identified CDRH3 motif could be used for vaccination.